Last update:
01-Mar-2001

Arch Hellen Med, 17(5), September-October 2000, 477-490

REVIEW

Proliferation and apoptosis of germ cells

R. ANGELOPOULOU, V. KARAYIANNIS
Laboratory of Histology and Embryology, Medical School, University of Athens, Greece

Cell proliferation and apoptosis are observed at various phases of gametogenesis and are important for germ cell development and differentiation. Numerous factors are involved in the control of both processes acting in concert to ensure the normal evolution of spermatogenesis and oogenesis. Apoptosis is the main cause of elimination of germ cells during the fetal period in both sexes. In the female, it follows the phase of intense proliferation and the entry into the meiotic prophase I. In the male, it occurs later, during the perinatal and the prepubertal period. The quantitative distribution pattern of Ki-67 protein and the proliferating cell nuclear antigen (PCNA) are used to investigate mitotic activity in gonadal biopsies during the reproductive period. Τhe characteristic morphology of the apoptotic cells detected by the electron microscope and the in situ 3’ end labeling procedure of nuclear DNA fragmentation enables their localisation on histological sections. The observation of low molecular weight DNA after gel fractionation and electrophoresis provides biochemical evidence of apoptotic cell death in the germ cells while quantitative estimation is made by flow cytometry. Recent advances in the understanding of the mechanism of apoptosis, the regulating role of the pro-apoptotic and anti-apoptotic genes and the different families of proteins involved in normal gametogenesis, along with analysis of the factors implicated in apoptosis of the testis and sperm in association with cell proliferation under normal conditions, should elucidate the mechanisms ensuring gonadal homeostasis and reveal the causes of infertility.

Key words: Apoptosis, Cell proliferation, Germ cells, Oogenesis, Spermatogenesis.